Soil mechanics of the potentially expansive clays in Poland

This paper is an attempt to evaluate the expansivity of the main genetic types of Polish clays which very often are considered as a bedground for engineering structures. Lithological characteristics and basic physical properties presented in this paper concern the soils of (I) Quaternary age: Boulder clays and glaciolacustrine clays, (II) Tertiary continental and marine clays: Mio-Pliocene clays of Poznan series, Miocene clays of the Carpathian Foredeep (unweathered and weathered), bentonites and bentonitic clays, oligocene clays of Szczecin area and Carboniferous bentonites (Tables 1 and 2). Based on the indirect methods described by Van der Merwe (1964) and Seed et al. (1962) nomograms were used to evaluate potentially expansive soils. Information obtained includes correlation between potential expansiveness (PE), degree of expansion (DE), swelling potential (5) and the percentage content and mineral composition of the clay fraction. Graphic illustrations are presented in Figs. 1–7, which also include nomograms for the approximate estimation of the value of swell pressure (σsp). The evaluation of potential expansivity of clays in Poland plays a key role in the design of engineering structures and in site selection.